Depends on the target market.
If you're looking at hardened tea drinkers, you'd want to specialise in a particular type of tea. If you aim to serve all ranges of experienced tea drinkers a small selection of nice tea from all the major tea types but not too expensive is good... Supply our everyday tea drinking (specific emphasis on greens and Oolongs I would imagine).
Then you have novice drinkers and a broad range of selection is good, of green, oolong, black and herbals.. Maybe a small selection of puerh and specific types of each, or maybe one very nice tea from each type ... Obviously a casual tea drinker just wants nice tea to be brewed western
I'm middle of the range, I most frequently buy tea for everyday drinking (both gongfu and western) and I'm a heavy oolong/green/black tea drinker on a multiple times a day scale
Puerh and nicer oolong are the Saturday/Sunday really nice gonfu sessions
Hope that helps XD